Bovine Serum Albumin-Dependent Charge-Transfer Kinetics Controls the Electrochemical Immunosensitive Detection: Vibrio cholerae as a Model Bioanalyte

Abstract

Graphical Abstract This work investigates how bovine serum albumin (BSA), a commonly used protein in the fabrication of electrochemical immunosensors, can impact on the sensitivity of detection when integrated with antibody (Ab) pre-encapsulated with (i) insulating polyacrylonitrile (PAN) fibre (i.e., GCE-PAN-Ab-BSA immunosensor) or (ii) conducting PAN-grafted iron (II) phthalocyanine (FePc) (i.e., GCE-PAN@FePc-Ab-BSA immunosensor), using Vibrio cholerae toxin as a case study bioanalyte. Both immunosensors show different charge-transfer kinetics that strongly impact on their immunosensitive detection. From the electrochemical data, GCE-PAN-Ab-BSA is more insulating with the presence of BSA, while the GCE-PAN@FePc-Ab-BSA is more conducting with BSA. The CV of the GCE-PAN-Ab-BSA is dominated by radial diffusion process, while that of the GCE-PAN@FePc-Ab-BSA is planar diffusion process. The behaviour of GCE-PAN@FePc-Ab-BSA has been associated with the facile coordination of BSA and FePc that permits co-operative charge-transport of the redox probe, while that of the GCE-PAN-Ab-BSA is related to the interaction-induced PAN-BSA insulating state that suppresses charge-transport. As a consequence of these different interaction processes, GCE-PAN-Ab-BSA immunosensor provides higher electroanalytical performance for the detection of Vibrio cholerae toxin (with sensitivity of 16.12 Ω/log [VCT, g/mL] and limit of detection (LoD) of 3.20 × 10 −13 g/mL compared to those of the GCE-PAN@FePc-Ab-BSA (4.16 Ω/log (VCT, g mL −1 ) and 2.00 × 10 −12 g/mL). The study confirms the need for a thorough understanding of the physico-chemistries of the electrode platforms for the construction of immunosensors. Although this work is on immunosensors for cholera infection, it may well apply to other immunosensors.

Electrochemical Immunosensor for Ultra-Low Detection of Human Papillomavirus Biomarker for Cervical Cancer

“…The fabrication of the HPV-16 L1 immunosensors and antigen–antibody interaction mechanisms are described in the Experimental Section but summarized as shown in Figure . The HPV antigen or antibody is immobilized onto the OLC- or OLC-PAN electrode via the conventional covalent bonding process through the formation of the strong amide bond using the sulfo-NHS ester. ,− In practice, route A describes the screening of HPV-16 infection (asymptomatic individuals), while route B is for the testing of the HPV-16 infection (in individual who presents some symptoms).…”

“…Figure summarizes the fabrication of the sensor. GCE was modified using the drop casting method following a reported method. ,, Briefly, 10 μL of electrocatalyst was drop-casted onto GCE and was dried in an oven at 45 °C for 30 min, and this was labeled as GCE-OLC-PAN . The GCE-OLC-PAN was functionalized with 3 M NaOH for 2 h, the electrode was washed with Millipore water and PBS, after which the functionalized electrode was dried with N 2 gas, to afford a carboxylic acid functionalized surface (GCE-OLC-PAN-COOH).…”

Onion-like Carbons Provide a Favorable Electrocatalytic Platform for the Sensitive Detection of Tramadol Drug

“…In 2002, Keller et al reported the first use of OLC as a catalyst for the synthesis of styrene. There are few reports on the use of OLC in electrochemistry, especially in the field of energy storage, − but its use in electrocatalysis has rarely been explored. − This work shows that OLC is a viable carbon catalyst for tramadol detection compared to the CB counterpart. Preliminary theoretical insights (DFT calculations) predict that the possible reason for the high electrocatalytic performance of the OLC is that the adsorption energy of tramadol onto the surface of OLC is weaker than on the surface of CB.…”

Ultrasensitive electrochemical immunosensor for the detection of C-reactive protein antigen

“…Subsequently, the physically absorbed antibodies were rinsed with PBS to remove the unbonded antibodies. The final coordination with the -NH 2 group of CRP-AB was obtained, with the amine-reactive sulfo-NHS ester groups on the working electrode, to form amide (-CONH-) bonds between the antibodies and the electrode, 44,45 which produced CRP-AB/OLC-PAN/GCE. Thereafter, any unreacted groups and nonspecific sites on the modified surface were deactivated and blocked by incubating the substrates in bovine serum albumin (BSA) 5% (w/v) for 2 h at 37 °C in a 0.1 M PBS ( pH = 7.4), to prevent false positive binding.…”